The effect of inhomogenities on single molecule imaging by hard XFEL pulses

TL;DR

This study investigates how inhomogeneities like heavy atoms and density fluctuations in biological samples affect atomic distortions during XFEL imaging, impacting image quality and correction strategies.

Contribution

It reveals the significant impact of inhomogeneities on atomic distortions and their evolution during XFEL exposure, highlighting the need for correction methods.

Findings

Local distortions around heavy atoms are larger than in the light matrix.

Density fluctuations significantly alter atomic displacement dynamics.

Inhomogeneities have serious consequences for single particle imaging.

Abstract

We study the local distortion of the atomic structure in small biological samples illuminated by x-ray free electron laser (XFEL) pulses. We concentrate on the effect of inhomogenities: heavy atoms in a light matrix and non-homogeneous spatial distribution of atoms. In biological systems we find both. Using molecular-dynamics type modeling it is shown that the local distortions about heavy atoms are larger than the average distortion in the light matrix. Further it is also shown that the large spatial density fluctuations also significantly alter the time evolution of atomic displacements as compared to samples with uniform density. This fact has serious consequences on single particle imaging. This is discussed and the possibility of a correction is envisaged.